Lubricating oil and process for improving same



Patented Jan. 11, 1938 UNlTEll STATES PATENT OFFICE.

LUBRICATING 011. AND raocnss FOB. nu-

. rnovmo SAME Melvin A. Dietrich, Wilmington, DeL, assignor to v E. I. du Pont de Nemours & Company, Wilmington, DeL, a'corporation of Delaware No Drawing. Application August 29, 1936. Serial No. 98,578

. 18 Claims. v.(oi. 87-9) This invention relates to improved lubricating use of these polymers results in a minimum 'oils and to processes for improving lubricating amount 01' undesirable'thlckening action on the oils. oils.

It is well known that lubricating oils, during These compounds may be represented by the 5 use. have a tendency to form sludge which is ex formula 5 'tremely undesirable. It has been proposed to I add various compounds, particularly phenolic E compounds, to lubricating oils to-improve their stability against sludge formation wherein R represents an alkylene radical, R1 represents hydrogen or an alkyl radical and R: an

It has also been proposed to add various ma- 1o;

terials to lubricating oils for the purpose of img i gg f'gg gigggg gg flg fig g ggggg 5 proving the viscositytemgera'ture relationships amino alcohol contains a tertiary nitrogen atom which relatmnsmps are indwated by the in which the substituents attached to the nitroindex. Among the materials which have been gen are aliphatic hydrocarbon radicals The proposed for this purpose have been rubber polymeric esters derived from N-substituted 15 hydrogenated rubber and highly polymerized amino alcohols in which the substituents are dmcarbons generally such agents have been aliphatic hydrocarbon radicals of at least 4 carmore or less successful but have the undesirable hon atoms will mgeneral be found to be property of havmgapponounced thickening efiect ciently solubledn the oil as the free base and .20 on the 011s hence can be used as such; whereupon they not- An object of the present invention is to provide om y stabilize the oil against oxidation and sludge n compounds 9 addition t lubflcatmg ofls formation but also improve its viscosity-temperato improve theresistance of the oils to oxidation. ture relationships. The polymeric esters derived sludgmg' A further object/ls to provide from amino alcohols containing a. lesser numcompounds to be added to 0115 which will ber of carbon atoms'will be less soluble in the 25 prove. the resistance of the q and oils and it will generally be necessary to employ sm-dgmg 1 also impmve the vlswmw'tempem" these polymers in the form 01 long-chain fatty ture relationships 01 the oils. A still further obacid salts m order to render them sumclenfly Jam; 15 to Pmvid? lubricating oils having soluble to enable the desired amount to be added proved resistance to oxidation and sludging or and retained in the on 30 improved resistance to oxidation and sludging when aliphatic and u y n radicals are viscosity'tempemture relation ierred to herein and in the claims it will be unships; Other objects are to provide new compoderstood that such terms include yclmaupham sitions oi matter and to advance the art. Still such as cyclohexyl and pentamethyl, as wen other oblects will appear hereinafter' straight and branched chain aliphatic radicals. 5

These objects may be accomplished in accord- Also the term u h i fatty acid" as ance with our invention by incorporating m ployed herein and in the claims, means the alilubricatmg oil, preferably a mineral lubricating phaflc acids of 8 or e carbon atoms small amount of a compound selected m The concentration of the polymer in the oils 40 the polymerized, acrylic and alpha will be. determined by the nature and character- 40 alkyl substituted acrylic acid esters of amino alof the on and by the nature and the degree cohols and oil-soluble long-chain fatty acid salts of improvement which is desk-m1 w n the or polymerized acrylic and alpha-alkyl substitutcompounds are added solely for improving the ed acrylic l esters while resistance of the oil to oxidation and sludge ior- Polymers hflvmg molecular weight as 800 mation, a concentration of about 0.5% to about" 45 y be used, it is prefer to mp y those 2% will generally be suflicient. When the coming a molecular weight of 2000 or more, particupounds are added for improving th viscositylarly for improving the vis s tye atu temperature relationships, amounts as high as lationships of the oils- The compounds of this 30% may be employed. However, it will in gen type ha been f u t be v y effective for oral be preferred to use between about 1 toabout 50 stabilizing the. mineral lubricating oils against 10% based on the oil. It hasbeen found that color formation, oxidation and sludge formafrom bout 1% to about 2% is satisfactory in tion during use. In additi n, the free bases have most cases, both for inhibiting sludge formation the desirable property of improving the visand improving the viscosity-temperature relacosity-temperature relationships oi the oils. The tionships. I 55 While it is preferable to add the polymer to the oil, a similar eifect may be secured by dissolving the monomer in the oil and subsequently polymerizing it, or by adding the constituents necessary to make the monomer to the oil by causing the constituents to react and polymerize directly in the oil. The compounds may be incorporated in the oils by adding them to the oils at 150 C. with vigorous stirring.

In order more clearly to illustrate this invention the preferred modes of carrying the same into eflect and the advantageous results thereof, the following examples are given:

.Ezample I 10 parts of a mineral lubricating oil containing 0.6% of beta-dicyclohexylaminoethyl methacrylate polymer were heated in a flat bottom dish at 135 C. for hours in the presence of a results.

' Example 11 10 parts of a mineral lubricating oil containing 0.50% of the stearate of polymerized betadiethylaminoethyl methacrylate were treated as in Example I. In this case, also, the oil darkened only slightly and deposited no sludge. The free polymer was difllcultly soluble in the oil and hence the stearate was employed to improve its solubility.

Substitution of the corresponding acrylate polymer for the stearate of polymerized betadiethylaminoethyl methacrylate in the above experiment gave analogous results.

Example III 2 parts of beta-dicyclohexylaminoethyl metha- 98 parts of mineral lubricating oil by heating the mixture to 150 C. with stirring. The improvement in the viscosity-temperature relationship of the oil was measured by determining the viscosity at 100 F.

and 210 F. and calculating the viscosity index according to the method described by Dean and Davis in Chem. and Met. Eng. 36, 618 (1929). This index serves as a measure of the flatness of the viscosity-temperature curve of the oil, increasing values of the index resulting as the curves become flatter. The flatness of the curve is a measure of the suitability of the oil as a lubricant over a wide temperature range. The results of this test are shown in the following table:

The above examples are illustrative only and are notv to be construed as limiting the invention. Various other materials of the same class may be employed, for example, thepolymers of esters of acrylic and methacrylic acids derived from other amino alcohols such as beta-propylamino ethanol, beta-di-isopropylamino ethanol, betadi-n-propylamino ethanol,. beta-dilaurylamino ethanol, gamma-diethylamino propanol, deltadiethylamino butanol, delta-dibutylamino butanol, delta-di-isobutylamino butanol, beta-diisobutylamino ethanol, beta-ethylamino ethanol, gamma-methylamino pr'opanol, delta-butylamino butanol, delta-isobutylamino butanol, beta-cyclohexylamlno ethanol, beta-(methylcyclohexyl) aminoethanol, aminocyclohexanol and similar amino alcohols.

Also, polymers derived from esters of other alpha hydrocarbon substituted acrylic acids which may be used are: alpha-ethyl acrylic esters, .alpha-propyl acrylic esters, alpha-isopropyl acrylic esters, alpha-butyl acrylic esters, alpha-amyl acrylic esters, alpha-hexyl acrylic esters, alpha-cyclohexyl "acrylic esters, alpha.- hexahydrotolyl acrylic esters.

When it is desired to use the it will generally be found preferable to employ the salts of stearic, palmitic, oleic and naphthenic acids.

Among other polymers which may be employed as the free bases or as the salts may be specifically mentioned:

2-aminocyclohexyl methacrylate, beta-N-dibutylaminoethyl methacrylate, beta-dimethylaminoethyl methacrylate, 2-diethylaminocyclohexyl methacrylate, 1(beta-methacrylyloxyethyl) piperidene, 4(beta-methacrylyloxyethyl) morpholine, didodecylaminoethyl methacrylate, dioctylaminoethyl methacrylate, (l-beta-acrylyloxyethyl) piperidene, gamma-diethylamlno- N-propyl acrylate.

The compounds of this invention may be prepared by reacting an acrylic or an alpha-alkyl substituted acrylic acid, its anhydride, acid halide or ester with an amino alcohol or amino alcoholate in an inert solvent such as benzene. toluene and the like under reflux. The resulting compounds are preferably polymerized by first converting them to salts and then subjecting the salts to polymerizing conditions.

'In order more fully to illustrate the method, the following example is given:

Example IV A solution of one mol. of beta-diethylamino ethanol, 4 mols of methyl methacrylate, 500 grams of dry benzene and 30 grams of p-plienylenediamine was prepared. This solution was heated in an oil bath under a 48". fractionatlng column fitted with a distilling head arranged for controlling the reflux. :As soon as the removal of the water, in the'form of the water-benzene binary, was completed, 2 grams of sodium in 20 cc. of dry methanol were added dropwise to the refluxing reaction mixture over a period of 6 hours. The benzene-methanol binary was collected at the head of the column. Upon completion' of the reaction, the mixture was cooled, filtered, and fractionally distilled. The fraction boiling at plus or minus 5 C. at 5 mm. was collected. This fraction, after washing and drying, was used for preparation of the polymer. While numerous polymerization catalysts may be used, the preferred procedure consists in converting the monomer to the acetate salt in aqueous solution, adjusting to 10% concentration, add g 1% of powdered benzoyl peroxide based on t e monomer, and heating for 24 hours at C. The resulting material, purified by filtration, washing, and drying, is converted to fatty acid salts the free polymeric base by mixing with an excess 75 ofsodium bicarbonate and heating to liberate carbon dioxide.

The,precipitated polymer may be converted into a fatty acid salt by solution inethanol iollowed by addition of the theoretical amount of the acid, forexample, stearic acid. The methods of preparing these compounds are described in more detail in the applications of G. D. Graves, SeriahNo. 21,807 flied May 16, 1935 and Serial'No. 42,054 filed September 25, 1935, and the application of J. Harmon,Serial No. 21,810-flled May 16,- 1935. These three applications also disclose many other compounds falling within the scope of this invention and which may be used for applicant's purpose.

While the preferred embodiments of this invention and the preferred modes of practicing the same have been disclosed, it will be apparent to those skilled in the art that many modifications 'may be made therein without departing from, the spirit thereof. Accordingly, this invention is to be limited solely by the appended claims, construed as broadly as is permissible in view of the prior art.

I claim: l. A lubricantcomprising a lubricating oil having incorporated therein a small amount of a compoundhaving a molecular weight of at least N-aliphatic substituted mono-hydric amino alcohols devoid of substituents other than aliphatic hydrocarbon radicals.

2. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble poly-- merized alpha-alkyl substituted acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

3.'A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-methyl acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

4. A lubricant comprising a lubricating oil having incorporated therein a small amount of a .compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

5. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized aipha-alkyl substituted acrylic acid ester of anamino alcohol in which the amino nitrogen carries at least 1 aliphatic hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

6. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least ,800, which compound is an oil-soluble polymer ized acrylic acid" ester of an amino alcohol in which the amino nitrogen carries at least 1 aliphatic hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

7. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-methyl acrylic acid ester of an amino alcohol in which the amino nitrogen carries at least 1 aliphatic hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

8. A lubricant comprising a lubricating oil; having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymer-' ents other than aliphatic hydrocarbon radicals.

9. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of 'at least 800, which compound is an oil soluble polymerized alpha-alkyl substituted acrylic acid ester of v a mono-hydric N-di-cyclohexyl amino alcohol,

which amino alcohol is devoid of substituents other-than aliphatic hydrocarbon radicals.

10. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular Weight of at least 800, which compound is, polymerized beta-(N- dicyclohexyl) aminoethyl methacrylate.

11. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble longamino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

13. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol de-i void of substituents other than aliphatic hydrocarbon radicals.

14. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain.

fatty acid salt of a polymerized alpha-alkyl substituted acrylic acid ester of a mono-hydrie N- di-aliphatic amino alcohol in which each aliphatic substituent is a hydrocarbon radical, the aliphtic substituents containing a total of at least 4 carbon atoms, and which amino alcohol is devoid of substituents other than aliphatic hydrocarbon radicals.

15. A lubricant comprising a lubricating oil having incorporated therein a small amount oi a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized alpha-methyl acrylic acid ester of a mono-hyd'ric N-di-aliphatic amino alcohol in which each aliphatic substituent is a hydrocarbon radical, the aliphatic substituents containing a total of at least 4 carbon atoms, and which amino alcohol is devoid 01' substituents other than aliphatic hydrocarbon radicals.

16. A lubricant comprising a lubricating Oil having incorporated therein a small amount of a compound having a molecular weight 01' at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized beta-diethylaminoethyl methacrylate.

17. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is the stearate of polymerized diethylaminoethyl methacrylate.

18. A lubricant comprising a lubricating oil having incorporated therein a small amount of a MELVIN A. DIETRICH. 

